Are diesel vehicles with AdBlue® tanks top of the class in nitrogen oxide emissions tests?
The European Commission sets nitrogen oxide emission control tests for diesel cars
The New European Driving Cycle (NEDC) benchmark test was implemented in the 1970s to certify diesel vehicles based on their nitrogen oxide (NOx) emissions. Subjected to these tests, diesel vehicles perform badly with regard to NOx regulations. Manufacturers actually prefer to flirt with the limits by installing cheating software—think Volkswagen—or electronic emissions management devices like Renault.
Temperature: the main variant for results
Temperature has an enormous influence on the effectiveness of pollution control systems. Therefore, manufacturers need effective pollution control systems to pass the NEDC certification test in the laboratory at temperatures between 20°C and 30°C. Renault points out that its pollution control system is no longer effective below -17°C or above 35°C. The Daimler system cuts out as soon as the temperature drops below 10°C.
Not all pollution control systems are effective in real-life conditions
In France, 14 out of 52 models have abnormal results at the end of a procedure that is only slightly different to the official cycle. The Nissan Qashqai exceeds the standard by 266%. For example, manufacturers give the combined fuel consumption achieved under laboratory conditions when engines are cold and acceleration is slow. Vehicles often emit five to six times more harmful gases than the maximum threshold achieved in the laboratory.
Diesels fitted with an SCR system that uses AdBlue® are more effective at reducing NOx emissions
The SCR (Selective Catalytic Reduction) system is championed as the most effective for meeting future anti-NOx standards. Indeed, cars equipped with an AdBlue® tank that powers the system achieve glowing results in the NEDC tests.